Mll4-flox. Conditional knockout mice for the histone methyltransferase Mll4 (Kmt2d) will help understand its role as a tumor suppressor.

Mono- and di-methylations on histone H3 lysine 4 (H3K4me1 and H3K4me2) are epigenetic marks for transcriptional enhancers, which control cell type-specific gene expression. Mll4, also known as Kmt2d (lysine (K)-specific methyltransferase 2D), is a major mammalian histone H3K4 mono- and di-methyltransferase enriched on enhancers (http://www.ncbi.nlm.nih.gov/pubmed/24368734). Mll4 knockout mice are early embryonic lethal, so we have generated Mll4 conditional knockout mice (Mll4-flox) in which exons 16-19 are flanked with loxP sites. Mll4 has been found to be a tumor suppressor gene mutated in a wide variety of human cancers. The Mll4-flox mice provide a valuable tool to study how Mll4 functions as a tumor suppressor and as an epigenetic regulator of cell-type-specific gene expression, cell differentiation and mouse development.